Zynga is preparing to launch RewardVille. Not a game.. But another attempt at a rewards program apparently designed to let users earn rewards for playing any of the many games made by Zynga! You will then be able to spend their "zCoins" on numerous items for any of the games you play!
Zynga recently purchased RewardVille.com which now points to rewards.zynga.com which announces the rewards program is in beta testing and you should keep playing their games and keep a heads up for their launch.
If you were part of the zLotto program that they had a few months back you have already registered and can use the same login info for this program too.
Here is a preview of the items you can purchase with your zcoins:
Here is the RewardVille FAQ that was on the Zynga Site until the other day..
zPoints and RewardVille Overview..
How to Earn zPoints